Basic Dysrhythmia Workshop Part I

Vocabulary flashcards covering cardiac structures, coronary blood flow, properties of cardiac muscle, electrical conduction system, cardiac cycle, and autonomic nervous system regulation from the Basic Dysrhythmia Workshop Part I lecture notes.

Endocardium

The innermost layer of the cardiac wall structure, consisting of smooth endothelium lining the inside of the heart.

Myocardium

The middle muscular layer of the heart wall responsible for cardiac contraction; it consumes $70\%$ of oxygen in the blood.

Epicardium

The outer layer of the heart wall, also referred to as the visceral pericardium.

Layers of the Heart

The structural layers composing the heart wall, including the endocardium, myocardium, epicardium (visceral pericardium), and parietal pericardium.

Cardiac Structures

The anatomical components of the heart, including four chambers (right atrium, right ventricle, left atrium, left ventricle), two atrioventricular valves (tricuspid, mitral), and two semilunar valves (aortic, pulmonic).

Right Coronary Artery (RCA)

Artery that supplies the right atrium, right ventricle to the inferior surface of the heart, the SA node in $55\%$ of people, the AV node in $90\%$ of people, internodal tracts, and the posterior third of the septum.

Left Main Coronary Artery (LCA)

Primary left coronary vessel that divides into the Left Anterior Descending (LAD) artery and the circumflex artery.

Left Anterior Descending (LAD) Artery

Branch of the LCA that supplies the interior surface of the heart, the anterior wall of the left ventricle, the anterior $\frac{2}{3}$ of the septum, and both right and left bundle branches.

Circumflex Artery

Branch of the LCA located between the left atrium and left ventricle around the lateral aspect, perfusing the left atrium, lateral and posterior left ventricle, SA node in $45\%$ of people, and AV node in $10\%$.

Coronary Blood Flow

Vascular supply originating at the aortic valve on the epicardial surface that travels into the myocardium and endocardium to perfuse cardiac cells, best perfused during diastole.

Cardiac Cycle

The rhythmic repetition of the mechanical pumping action of the heart in response to electrical stimulation, consisting of two phases: systole and diastole.

Systole

The contraction phase of the cardiac cycle where actin and myosin are released by calcium to allow crossbridge overlap, causing the aortic and pulmonic valves to open.

Diastole

The relaxation phase of the cardiac cycle where ventricles fill with blood, stretching actin and myosin crossbridges, while the mitral and tricuspid valves open.

Frank-Starling Law

The physiological principle stating that the force of myocardial contraction is dependent on the amount of stretch on actin and myosin prior to release.

Automaticity

The unique inherent property of cardiac cells to initiate an electrical impulse and contract without nervous stimulation.

Excitability

The ability of cardiac muscle cells to respond to electrical stimulation.

Conductivity

The ability of cardiac cells to transmit an electrical impulse or energy through the heart.

Contractility

The ability of cardiac muscle cells to shorten as a result of electrical stimulation.

Electrical System of the Heart

The conduction network comprising the SA node, internodal tracts, Bachmann's bundle, AV node, bundle of His, bundle branches, and Purkinje fibers.

Sinoatrial (SA) Node

The primary pacemaker of the heart located at the junction of the right atrium and superior vena cava, with an inherent rate of $60\text{--}100\,\text{beats/min}$.

Sinus Rhythm

A cardiac rhythm produced when the electrical impulse originates in the SA node.

Atrioventricular (AV) Node

Conduction tissue located at the junction of the right atrium and ventricle that delays impulses and has an inherent rate of $40\text{--}60\,\text{beats/min}$.

Junctional Rhythm

A cardiac rhythm originating in the AV node (also called nodal rhythm).

Bundle of His

Conduction tract that connects the AV node with the right and left bundle branches.

Purkinje Fibers

Fingerlike projections into the ventricular muscle that transmit impulses into every cell in the ventricles, with an inherent rate of $30\text{--}40\,\text{beats/min}$.

Autonomic Nervous System

The neural regulation system composed of sympathetic and parasympathetic nerves that modulate cardiac rate, conduction, and contractility.

Sympathetic Nervous System (SNS)

Division of the ANS regulating 'fight or flight' responses; affects atria and ventricles via epinephrine and norepinephrine to increase SA node rate (Beta 1), AV conduction, cardiac contractility (Beta 1), and cause arteriolar vasoconstriction (alpha).

Parasympathetic Nervous System (PNS)

Division of the ANS that dominates under stable conditions; affects only the atria via the Vagus Nerve and acetylcholine to decrease SA node rate (chronotropic), AV conduction, contractility (ionotropic), and irritability while causing vasodilation.